Polyesters, particularly those used for food and beverage packaging, have some very desirable features, such as safety and low cost of transportation. However, when these containers are not recycled or are improperly discarded, they represent an aesthetic blight on the landscape. Therefore, it would be very desirable to develop a polyester that retains the useful properties of these polyester packages but would dissipate spontaneously in the environment when discarded improperly.
One approach to this problem would be to take advantage of the degradative effect of the strong ultraviolet radiation emitted naturally by the sun. It is already known in the art that the introduction of some ketone-containing moieties into a polyester chain gives an ultraviolet sensitivity to polyesters, causing them to become brittle in the process. The brittleness causes the polyesters to crumble and ultimately dissipate.
Reportedly, the degradation requires shorter wavelength ultraviolet radiation, generally in the range of 280-320 nanometers. These wavelengths are generally filtered out of the spectrum by ordinary glass. Therefore, since the requisite ultraviolet wavelengths are not present in indoor environments, the rate of degradation indoors would be very slow.
We have discovered ketones which introduce ultraviolet sensitivity to a polyester.
U.S. Pat. No. 4,965,399 discloses 1,5-bis(substituted-aryl)-3-pentanols which are useful in the preparation of polymeric materials.
U.S. Pat. No. 5,025,086 discloses 1,5-bis(4-carboxycyclohexyl)-3-pentanol and its esters and processes for their preparation.
U.S. Pat. No. 3,878,169 discloses polyesters which contain ketone groups in the side chains, but not in the backbone of the polyester.
It has heretofore been unknown to use ketones such as those used in this invention as a repeating unit in the structure of a polyester.